Isolated Osteochondromas of the Inner and Outer Tables of the Ilium: A Report of two Rare Cases

Introduction: Osteochondromas are common benign bone tumors that usually present in the second or third decade of life with a slight male predilection. They may be isolated or multiple and frequently arise from the metaphyses of long bones. Rarely, they arise from atypical sites such as the scapula or pelvis. They are frequently asymptomatic and can be managed conservatively through serial monitoring and expectant observation, although en bloc excision, preferably following attainment of skeletal maturity, is advisable for symptomatic patients. Osteochondromas of the ilium are extremely rare, with few reports in the literature. Their management can be challenging, depending on their location and proximity to adjacent viscera and neurovascular bundles. Case Report: We report the management of two patients with isolated pedunculated iliac osteochondromas. The first was a 13-year-old skeletally immature (Risser grade 0) boy who presented with a swelling over the right hemipelvis and limitation of hip movements. Radiographic and magnetic resonance imaging (MRI) evaluation was suggestive of an osteochondroma over the inner table of the middle third of the ilium, in close proximity with the ascending colon. The second patient was a 19-year-old skeletally mature (Risser grade 5) boy who presented with complaints of a swelling over the right hemipelvis with pain on terminal hip range of movement. Radiographic and MRI evaluation was suggestive of an osteochondroma over the outer table of the anterior third of the ilium, slightly posterior to the anterior superior iliac spine. Both patients underwent en bloc surgical resection of the tumor. The first patient required additional repair of the anterior abdominal wall musculature, which required dissection for exposure of the tumor. Histopathologic examination confirmed that the lesions were osteochondromas. Both patients were asymptomatic with no evidence of tumor recurrence at their most recent follow-up. Conclusion: Surgical excision of osteochondromas of the pelvis may be required for symptomatic patients, as well as asymptomatic patients when the tumor lies in close proximity with vital structures and is progressively growing in size. Meticulous surgical planning can prevent perioperative complications and result in satisfactory outcomes, even in skeletally immature patients. Keywords: Osteochondroma, pelvic tumor, benign tumor, osteochondroma of ilium, bone tumor, en bloc excision.